Multiplex telegraph system



Sept. 14, 1943. L. M. Po'rTs MULTIPLEX TELEGRAPH SYSTEM Original Filed Jan. 18,1941 2 Sheets-Sheet l IO N INVENTOR.

LOUIS M. POTTS ATT Patented Sept. 14, 1943 .UNIIECB stares eaten-r torn-ca Q .aszasso fl "MULTIPIIEX"TELEGEAPH'SYSTEM iLouistMnRottsnEvamSton, lll eassignorrto iTleiei typerflorporatien, Ghicago lll -iaz corporation of Delaware 0riginal' application "January 1"8,-1-941,"Serial-N0. '--374;-991. '-Divided-and tilii gfplicatien llovcmber 2.1942, Serial N 8-,Glaims. (01

and gaf'branch jcircuit normally "c'onditionedifor start stop simplex'operation an'da meanstor condition.the system for synchronousgmultiplex operation'by the' addition of 'anotherrbranch' circuit to' the system. I

.A further object of this-inventioniis'to provi'de means to- ;convert from simplex operation to synchronous'multiplex operation and. vice versa 'withoutinterrupting'j transmission over the branch'circuit and main channel normally conditionedffor simplex operation.

Thisinvention features a main channel with which" abranch circuit is normally directly-connectefd for simplex operation'but with. whichanother branch vcircuit may be connected through a. distributor "for. synchronous multiplex operation. 2W'hen conditioned for synchrionousmultivthe-branch circuits at the sendplex ,operation, ing "and. receiving-terminals of themainchann'el areconnected therewith' through regularly operated contacts included in isynchronous. "distributors, which distributors operateand 'in' phase-With one-another. In each transmissionbran'ch 'rcircuit there is provided -a-'-startstop per-mutationcode transmitter. operable at random and-signal repeating mechanism "capable of generating two identical sets of signals ."which are sent :of phase with one .-'another. "There-is also zprovicled rme'ans WhiCh'ZuIIdeIl the dual: control .ofsthe. itransmitterztarrd'saz transmission :phasing -;cam included the multiplex distributor selects nd app ies to-sthesmain channehrim zxulse by; impulse, that set ofrsigna-ls rwhich is'iinesuitable; phase relation? withrthemultiplemdistributor contacts, inserting. a zvariable delaydnthe transmission circuit due :to [the eoperationaot the. repeatin-J mechanism.

.In the..firstembcdiment ,of the invention .the means ,toLcontrol .th'e -delay..in.,th transmission circuit and to properly phase the repetition. d1": transmitted "signalsto'the operation of'thefdistributorcontacts which connect the bIEHIchCirin 'synchron'isrn' cuits to the -main channel comprises a pair ef regenerative repeaters each of-Whi-chinse'rtya delay of haii a signal --'mpulseand a pair "of polar relays conditioned by tlie' transmitter and the distributor jointly to include Onebr brith regenerative repeaters in the branch cir'cjuit and to insert a delay of either one half impulse'or two'halfimpulses.

in the first modification -"0f the invention -=a ca-m-controlledmechanicarmeans is-employed in place "(ifQ/fiflllfflf polar-relays 'to control the delay in transmission by including; one-or both regenerative 'repeaters in the branch circuit.

-More specifically, the invention in one-app1ication embodiesa. plurality of --;'main channels to each:ofi'wliich is normaily connected for's-implex operation 'thereover, "a branch circuit and toreach -otwhic'h another branch circuit mayj-also be connected to'aifordsynchronousmultiplex operation and" allflthe main channelsmay, irrturn,

beconnected:'permanentiyto a-carrier' conductor to form a :carrier:telegraph system. Associated with each terminal *oi each mainchannel isl a mechanical distributor "which is disconnected l therefrom' during simplex toperation over -the main channel and one-branch'circuitfibut"which operates, 'when the synchronous multiplex operation' has'been established, to connect reach or the two {branch -circuits in alternation if or "half 'a, signal impulse period "with the main channel;

the connection bein-gthrough' aLPairnf-cam controlled contactst inthe: distributor; which op crates at "a'speed of :one revolution per signal impulse period.

In order to ,avoid interrupting the' simplex operation and mutilating :a signal combination, .a' relay :circuit operates-"to establish "synchronous.

multiplex operation only when the distributors arepperatin'g iniphasewith oneianotherxandat synchronous speed andin proper phase relation with. thetransmitter operating at. random? irrthe normal simplex circuit.

.The ftransmitter in each "branch circuit when the. system 'is connected for. multiplex operation operates at ramlorn but'the branch circuits are re ularly :connected' with .the' main "channel and signalirepeating mechanismgisjprovidedinieach branch 'circuit'to generate [signals in a suitable phase" relation" with the "operationof the *mxiltiplexfdistributor'contacts. The repeating mechanism iscontrolle'd jointly by the; phase' aofj the incoming signals arida transmitting phasirig c'am in the" multiplex distributor to p'hase" the-- output of the "repeater 'mehanisrn ivith -the opelr-ation of the multiplex distributor -c'onta-cts =and to stations of Fig. 1 to substations also designated in Fig. 2;

Fig. 3 shows a modification of the equipment of Fig. l, employing mechanical relays for controlling the repeaters;

Fig. 4 shows a further modification of the equipment illustrated in Fig. l with a combination repeater mechanism substitutedfor the plurality of repeaters in Fig. 1; V

Fig. 5 shows mechanical details foradjusting the followers associated with the distributor cams; and I a i Fig. 6 shows ia modifiedcamfollower adjusting mechanism. 7

Figs. 1 and 2 when combined present complete circuits illustrating one embodiment of a system employing this invention. In general, :cond u c tors I and} extend from Fig. 1 toFig. 2 and form a part of branch circuits'A and B, respectively.

Branch circuit A is termed a basic? circuit b ecause it is normally conditioned for simplexfoperation. Reference to Figs. 1 and 2 will show that conductor is normally connected directlyto conductor 3 of main channel C through the contacts ll at relay 55 completing a simplex communication path from a substation tomain channel C. Main channel is shown as part of a carrier telegraph system including a carrier conductor 51 to which the basiccircuit is extended over conductor -3 and, therefore, it is proper to call conductor 3 an extension conductor to which basic circuit A is normally connected.

Branch circuit B, is termed an .additive circuit because it is normally out of the telegraph system but may be added thereto. Conductor 2 of circuit B, for example, is normally interrupted at the outer right-hand armature of relay 55 and when relay 55 is energized, in a manner. to be hereinafter described, circuit B isadded to extension conductor 3 in alternation with basic channel I through a distributor 2| and its cam controlled contacts. a I Conductors and 6 also extend from Fig. '1 to Fig. 2..and are included in operating circuits of. the mechanism associated with the circuits above-. mentioned. Signaling conductor 9 also extends. from Fig. l to Fig. 2 and is utilized tofcontrol' lamps associated with circuit B.

Substation includes a transmitter |2 which may be tape controlled or a direct keyboardtype, a home recorder l3 and a receiving recorder l4. Other substations included in the system are simmotor 38 through gearing 39.

At 28 is represented a central oifice through which substations are connected for inter-communication. A transmitting distributor 2| is located at the central oflice and is driven from a speed controlledmotor 28 through gearing 29. The distributor includes a shaft 22 carrying cams 23, 24, andZ'! operative to establish and maintain synchronous operation over main channel C,

in a manner to be described hereinafter.

A distant central oflice is designated 30 and it is equipped with a receiving distributor 3| which comprises a shaft 32 driven by speed controlled Cams 33, 34, 36, and 31 carried by shaft 32 operate in synchronism with cams. on distributor shaft .22 during multiplex operation. I

Orientation between motor phasing cam 31 and distributor cams 33 and 34 is provided by hub 4| on cam 31, the hub being adjustably fixed to shaft 32 by set-screw 42. Rectangles 43 and 44 represent regenerative repeaters identical in construction with repeater l5 and controlled by, nonbiased, polar relays.

The description and mode of operation of the system illustrated. in Figs. .1 and 2 will be set forthfirst for its normal condition of operation, that is, simplex operation, and then for an alternative condition, such as synchronous multiplex operation. Accordingly, the normal operation wherein the distributors 2| and 3| are idle and wherein only the basic circuit A is connected for a simplex telegraph operation, is as follows:

Permutationcode start-stop signals for basic circuit A are generated by transmitter l2 at subilar. A regenerative repeater is symbolized in Fig. 1 at |5'and.may beef the type illustrated and described in United States Patent No. 2,105,- 173 issued to W. J. Zenner et: a1. and is characterized by the fact that code signals are repeated therefrom impulse by impulse witha time delay of about one-half'of an impulsewperiod with respect to received signals. Although a particular type of regenerative repeater is here disclosed, it is to be understood that the type described s station H and are transmitted over line conductor 5| to regenerative repeater l5, whence regenerated impulses flow through conductor 52, armature and lower contacts of polar relay 53, to storage repeater |6,' the twice repeated impulses flowing thence through conductor contacts I! of unoperated relay and extension conductor 3 to the winding of polar line relay 5B.

A source, of alternating current, 500 cycle alternating current for example, is connected to the upper contacts of polar relay 55 and is adapted to be applied to carrier conductor 51 through the armature of the relay 56. Accordingly, as

, relay 5i is actuated in response to signal impulses received over extension conductor 3 from transmitter pulses of 500 cycle alternating current are placed on carrier conductor 51 and thus the signal impulses are transmitted over the carrier.

The carrierconductor 5'1 extends the transmission circuit through hybrid coil 63 into a duplex'carrier transmission circuit 6|, equipped with echo suppressing networks 62. Through a similar hybrid coil 64 the signals are transmitted from duplex-circuit 6| into the carrier conductor 45 to tuned relay 65 which is characterized by the fact that it is responsive only to 500 c'ycle current impulses. Relay 65 repeats the signal impulses in the form of direct currents to polar relay 66 which repeats 'like'direct current signal impulses through extension conductor 61, conductor 68, outer contacts of unoperated relay 69 and regenerative repeater 43 to acme-5o ine conductor H and to receiving recorder. 12

If substation 13.

Transmission in the reverse ween substations l3 and-H is effected by transhitter M of substation l3, duplicates, of .regen- :rativerepeater l5, storage repeater l6 and distributor 2| represented by .rec-

circuit SI -coils 63 and Through the circuitsoutlined above, substa-' tions l and i3 normally are maintained in communication by means of carrier conductors l5 and. 51 andextension conductors 3 and 61. A130,, transmission circuit to. the carrier channel has associated with it only one: transmitter, the association being over a basic circuit, such as basic circuit A, associated with extension conductor 3- In other words, in this normal condition each transmitter which is connected tov the carrier channel, is connected therewith. over'a simplex: circuit.

lhe above-described operation is predicated upon the idle position of distributor 21 illustrated in Fig. 2, which conditioned the armatures: of relay 53 and 83 against their lower contacts and included both repeaters. l5 and l6 in the transmission circuit. Whendistributor 2k is. disconnected from extension conductor 3 with its cams displaced 180 degrees from the illustrated position, the normal, simplex transmissioncircuit is direct to channell from regenerative repeater 15 because in that position of the distributor 2|, the armatures of relays 53 and 83 rest against their upper contacts and break the circuit to repeater It at the armatureof relay 53. In additiomthereis completed from negative battery over a. circuit including the armature and upper contacts of relay 83 and repeater l6,v a holding circuit which holdsrepeater l6.

inoperative so long as the 'armat-ures; of relays- 53 and 83 remain against their upper contacts. Except for the omission of the repeater L6,;the transmission circuit is identical with that, Previously described.

The normal transmission circuit described v above, Whether it includes one. or both of theregenerator repeaters, interconnects substations H and 13 for communication over a: simplex.

circuit. vWith the communication circuit of the system in this condition, additive. circuit B is.

inoperative since conductor 2. terminates at the outerright-hand contacts of relay'fifi vhich are open.

The circuits and alternate condition the previously defined. addi-, ti've circuit is system'along with the basic circuit.

To initiate the operation of additive circuit B and thus establish the alternate condition,

, tributor shaft 22..

In its unoperated condition the. relay H2: through its outer right-hand contacts; has m ning;

direction.

6-5, distributor 3| Hand each extension conductor extending the their modeof operation fori the alternate condition of the .systemdisclosedin'Figs. 1 and 2 will now be described. I In this.

included in the "communication (motor 51'- lcyclercurrent tonthe tuned: relay I-22. to supply currentof positive polarity to polar .relays i231 and I and heldopen the energizing circuit of Upon being. energizedthrough the-operation' of key III, relay H2 interrupts the supply of 1600 cycle alternating current at its outer righthand contacts but that supply is maintained to carrier conductor. 51 through. controlled con-' tacts H6 at cam 21.. However,,.as -motor28-- d-rivesshaft 22,-cam 2T. breaks the supply circuit interrupting the 1600 cycle alternating'current and, consequently, releasing tuned: relay I22 whose armature :thenappli'es' negative battery to the circuit of relays I23 and r24. Ha

ing thusnchanged thepolarity of polar relays I23 and. I324; their amatures are conditioned againstftheir lower contacts and an energizing circuit isthereby completed for sl'ow-to-release. relay I25 including the armature lower.

contacts of relay I23. Relay lii'draws up its armature completing. an obvious circuit. which operates. relay l2! and. connects power conductors-l28 to motor 33 and starts the motor to drive shaft32."

Asmotor '28 increases :its speed, cam 21 K -throughyits, control'led contacts I 26- supplies pulses of 1609 'CYCIE": alternating current from conductor 121 to tuned relay I22 which responsive'ly supplies direct currents of alternating polarity to -relays 123 and .124 to cause their armaturesto vibrate; That is, when the 1 600 cycle" current is flowing, relay I22 operates and appliespositiy'epotential: to the circuit of relays I23 and I24 conditioning their armatures against their upper contacts; but when that IGOOEcycle current is interrupted through the rotation of cam 21,; armature of relay I22 applies negative battery to the relays I23 and 24 to" move their;armature's: against their lower contacts.

Relay l-25ris a3 slow-to-release relay to hold the 'ipower circuit. tormotor3fl' cl'osed through: the

armature of relaylflwhen the'armatu-re odl'relay l23"moves to-.its'rupper contactsand thus:

assure continuous operationof the motor 38.

In addition to controlling thesupply of power to motor 38 through relay-$21; the circuit oi' the 1699i cycle alternating current also functions as a synchronizing circuit to control tl respeedi'of motor 38; *As' explained above, the rotation of cam 21 causes the armature of relay H lto' vi- 7 brate and these Vibrations are employed in con junction. with. apair of cam controlled contacts l3|- and B2, controlled by cam 31', to apply a.

shunt 'acrossanarmatu-re resistance 33 togovcm the motor speed-r The'speed ofmotor 3 8 'is I decreased- When resistance 133 is: iii-the arm'ature'circuit. and; accordingly, inorder to regulate the motor speed, it. only necessary to control the length of the perioddurttng which resistance H3 is shunted out.

' In operation, when motors. erly synchrorrizedg; the vibrations of relay P24 in combination with the actuation of contacts 'HH and m determine the length or the shunting oe riod for iresi'stancielw in each position or armature-of relay in; Should (motor fid'tend'to increase in speedcam controlled contacts l-3iand t3.-2- would. open theshlumt-circuit earlierj shortening the shunted period of-resistanee I33: and decreasing.- the motor speed. 0n the other hand, if motor 38 should tend'tdlag'the cam QT tained conductor, I 21v connected to. carrier .0011;-

thus supplying an unbroken 1600'- v 28 and 38 are propwould not open the shunt circuit until a later instant in the cycle, elongating the shunt period and increasing the motor speed. In United States Patent No. 726,750 issued to L. M. Potts on April 28, 1903, there is disclosed and fully explained such a synchronizing system and-reference may be had to that patent for a more complete disclosure of the principles of such a system.

In addition to synchronizing motors 28 and 38, relay I24 and contacts I3I, I32 controlled by cam 31v assure the proper phasing of the distributors 2| and 3I since there is only one position in which shaft 22. can come into synchronism with shaft 32. I

Since in the particular embodiment of the invention under consideration the alternate condition contemplates synchronous multiplex operation, it is necessary to defer the establishment of the alternate condition until distributor motors 28 and 38 are operating synchronously,'and for the accomplishment of this result, means is provided, as will presently appear, to establish synchronous multiplex operation under the control of both distributor motors.

There is provided at central station 20 a plurality of relays, such as 54, one of which is associated with each extension conductor and which must be operated to convert the extension conductor from simplex to multiplex operation. The circuit for these relays is closed by slow-to-operate relay I36 when motor 28 has attained a predetermined speed. The energizing circuit for relay I36 includes the inner right-hand armature of relay H2, secondary of transformer I31, and rectifier I38. The primary of transformer I31 is in a tuned circuit to which alternating current is supplied through contacts I39 actuated by cam 21. Although there will be an alternating cur rent flowing through transformer I31 as the motor 28 comes up to speed, relayv I36 is not operated but only when the current of greater intensity which traverses the tuned circuit when the motor is at synchronous speed and voltage of resonant frequency is applied to the tuned circuit. Since relay I36 is slow-to-operate, it will not actuate until the motor 28 attains and holds its synchronous speed. When: relay I36 operates, the circuit including relay 54 and others (not shown) for the remaining communication channels of the system, is; completed, thus operating relay 54 preparatory to connecting basic circuit A and additive circuit B to extension conductor 3 through cam controlled contacts I52 and I51.

a signal impulse. Accordingly, a companion relay 55 is associated with each relay 54 to prevent such signal mutilation and maintain communication over the basic circuit even though the system is converted to multiplex operation. Continuing the description of extension conductor 3, basic circuit A, and additive circuit B for illustrative purposes, the operation of the companion relay 55 is as follows:

. '55 In each basic circuit there is provided as al- I and I51, respectively,

Relay 55 is a three-winding relay wherein the middle and right-hand windings energize the relay initially and the left-hand winding is a holding winding. The circuits for the energizing windings of relay 55 are: ground, cam controlled contact at I5I, polar relays 53 and 83, earn controlled contact at H9, conductor 5, cam controlled contact I53 to either line I29, armature I60 of relay 54, right-hand winding of relay 55 to positive battery, or to line I30, armature I6I of relay 54, center winding of relay 55 to negative battery. The circuits just described for the energizing windings of relay 55 include cam controlled contacts I5I and I I9 at repeaters I5 and I6, respectively. Upon the receipt by either repeater of the start impulse of a code signal combination, that repeater is set into operation and through a suitable cam. opens its cam controlled contacts and retains them open until the receipt of the stop impulse.

Relay I36 in addition to completing the circuit to relay 54, supplies the ground for the obvious holding circuit of relay 55 when the relay is energized including the left-hand winding, contact and inner left-hand armature of the relay 55. When relay 54 operates in response to the actuation of relay I36 by the distributor 21 rotating at the desired speed, armatures I60 and I6I are attracted rendering transmission phasing cam 24 effective to control the circuits of the energizing windings of relay 55. If at this instant no signal is being transmitted over the cuit A in the normal simplex circuit, the circuit to relay 55 will be completed through cam controlled contact I53 and either line I29 or I30. Accordingly, the center or right-hand winding of relay 55 will energize the relay, complete a holding circuit therefor through the left-hand winding and inner left-hand armature, complete an obvious circuit over line 9 and the outer left-hand armature of relay 55 for slow-to-operate signaling relay I45, and connect basic circuit A and additive circuit B through the right-hand armatures of relay 55 to cam controlled contacts I52 thus establishing the synchronous multiplex operation.

If at the time relay 54 draws up there is a signal being transmitted over the basic circuit, the energizing circuit for relay 55 will be interrupted at either cam controlled contact I5I or H9 and this condition will prevail until the entire signal combination has been repeated to extension con,

in the repeater for transmission, the circuit to relay 55 will again be completed at the cam controlled contacts I5I and H9 and relay 55 will be energized to establish the multiplex condition as described above. The circuit of relay 55, therefore, controlled jointly by the signaling condition of the basic circuit and the distributor mechanism delays establishing the multiplex operation until the stop impulse or no signal impulse is being transmitted over the basiccircuit. This assures continuity of transmission over the basic circuit and permits establishing synchronous multiplex operation without mutilating signals in the process of transmission over the basic circuit.

At central station 30, a plurality of relays 69 similar to relay 54 is provided, one for each extension conductor 61, and this plurality of relays is operative to condition the receiving extension conductors for multiplex telegraphy through the distributor cams. The circuit of relay 69 is under the dual control of relay'IM and tuned transbasic cirdetermined speed and tuned transformer relay: I 45. operates.

former-1 63 At MB th'ere isrepresented -a tuned transformer and an associated rectifier-to control rel-ay- Ill -in a manner identical tothatdeseribedin connection with relay 13B. 'Thealterhating current in this instance "is supplied through the armature of relay I23 and 1 its ire- "que'ncy isdetermined by the speed of motor "23 "through-"cam 21 and its-controlled contacts I38 which supplythe pulses for relay in and" consequently relay I23. When motor 133 is-at synchronous-speed, the frequency of this alternating current is the resonant frequency for the tuned transformer and its current operates relay Iii-i. With rel-ay- I 4 I energized, the circuitfotrelaffifi is closed. butthatrelay will'not be'operated until thealternating current generated at contact-5| 4&2 'under-thecontrol of cam 36 is at resonant'frequency for tun-ed transformer I 43 "A rectifier I44 is ineludedintherelay circuit and the operation "of the circuitto energize relay 6-9 is precisely the same as that described "for the operation ofrelay 1136 through ,contact' I39. Accordingly, it follows "that 'bothmotors'zt and38 must attain a predetermined speed, preferably synchronous speed, as 'a conditionprecedent'to .the energize.-

tionof relay.69. j 1

''lhesequence'of'events in starting the distributorsZ I.:and"'3 I. isasfcllows: The key N lLis closed momentarily, motor 28 starts notortii starts,

motor28. attains-predetermined speed,ir'elay I36 receives currentbut the slow-temperate arma- "ture of relay-T36 does not respond at once,v-armatureof relay-MI operates, motortt'iattains .pre-

I43 supplies .f current .torelay 69, Irelayffiii operates and energizeslrelays't. overan obvious circuit but the slowtoeoperate. armature of. relay 1% does not respond-atonce, armature of relay I36 operates .andsupplie'sfcu-rrent to relay-.54, relay- 54 operates, contacts. 1G0 :and. I6 I .are ..attracted, relay '55 is energized fduringthe stop signal period or .when no\ signal. 3 being-transmitted ,over basiccircuit through its left-hand A; s and supplies current slow -to-:opeiiaterelarmat-ure: and conductorv v9 to lay Hit-thearrnature of sMw-to-operaterelay. 96

armature -.:0f sloW-to-oper-ate The operation of th'ose'relays -efiects the following conditions to establish multiplex operation: '1 I sfUpontheoperationof relay- 69. the

operates, and. the

direct coni'nection between conductor-:Bihand regenerative -repeater-:43 is broken and -a substitute path is formed through left-handigcontact wcontrolledwby cam :33 and through outerrieft hand-armature of relay: 69 to repeater :43. Receiver zlzyat substation -ttxis now-connectedto extensionoonductor fi'l'for but a brieii interval :every: unitaryzsignal impulse -.period'zsince .idistribiitor shaft :32 was ave-ll;- as shaft :22- :completesi one 'rrevolution; each unitary. :signaliimpulse period. .Carn13'3is provided wane short recess so that onlyeaisnialllportion .of;a .zsignal; impulse is l'transmittediathereby. .Bycp-roperlymnienting the :cam iollowers it isxpossible to plckaoutithat .portion' of a. signal impulse which .ishleastswiect to distortion and :transmit that portion-toe repeatenand thus prevent trans m'itting'lwrong signals' therefrom.

every signal 'impulse period and permits the a polar relay of the regenerative repeater at 43 to be conditioned by -variable polar'ity voltage supplied' thereto from the armature oizpolar relay 68 regenerate these shorter impulses into full length impulses for propagation-over conductor -"H to receivingrecorder 12- at substation "l3. The contactsof distributor cam-33 will comeinto operation in phase with signals generated'initially'at substation -II, because the contactsef cams/21 and 31 will I have phased the distributor shafts 22 and az. l e --Wh'en slow-to-operate relay 1*3'3 -operates. it

5 l"! :be tween conductor"! and extension conductor- "'3 is interrupted and a substitute-pathis formed energizes relays w and 55 and theconnect-ion at from; conductor I th'roughinner right-handcontacts ofoperated relay 55 and-'contactsifiz boontrolledbyc-am 23 to extension conductor" 3,'thus including'distributor-contacts I'52 0f cam"23 in the 1 transmission pathof basic circuit, 'A. The

conduct-or know occupies but one'half of the time oi -extension conductor *3, the other half time being; nowavailable for the additive circuit 13 through cam controlled "contacts I-EI'IJThus the transmitting portion of the "system is "condi- -t-ione"d for synchronous -multiplex 'telegrap'hy; in *whichtransmission from basic "circuit A and additivecircuit B'over extension conductor 3 is impulse-by impulse with succeeding-signal impulses originating a'lternatelyincircuits A'andB.

When slow-to operate relay 95 operates, 1 its "armature connects the. transmission line '51 through to receiving recorder M5 "at' substation WI by means ofituned relayifiipolainrelay66, line 67, right-hand- 'contactscontrolled by cam 33, inner left-hand *armature'iof relay 69, armature of relay -*6, and regenerative repeater 44. "With additive circuit'B "connected in this manner with its receiverI4'6,'the synchronous multiplex sysoperated energizes lamp 134, indicating to the operator at station"M'WthatcQnductOriZ'is now periodsof 'operation'as is r equired'stolassurethe conditioned tor operation. Relays 396,136, and M5-- are "constructed or adjusted to such [delay closing ofvtheir contacts-in the desired order.

'-circuit utilizing regenerative'repeater M9, storage repeaterlfifl, alternativecontacts in relays/ and 13-9v and alternative contacts controlled by cams P23 and. "33, respectively and sharing the line time with'basiccircuit A.

As indicated previously, thereisfproyi'ded a means for changing'the polarity of the Power applied'to relays 53 "am-1'83 in order'zto vary'the positions-of theirrespectivenrmaturs. JIn the present embodiment, .a. contactv I 53 is actuated by a transmitting phasing cam '24 to .applypotential: over line 5 to relays 53. and 83,.and' there is included in this circuit; the .cam .controlled ;contacts at regenerative repeaterslfil and lise I that the circuit is operative onlylwhen. itis ,complated ateach repeater. .Under the influence of cam 24,".1contactfI-E i3 vibrates between cooperat- "ing contacts 1 to \-.apply alternately positive potential froni lina I-29- and negative potentialsfrom ,,-l-ine L30- tosthe-relaygcircuit. In ,likamanner,

Camtii closes Litslcontactstomeceiverri 2. for-but a short period in I there is alternately :zapplied positive and :nega

: t-ivepotentials.respectively from lines "I56iamzd: [-55 to contact 154, .=linerr6,'icamrconttrolledccontacts and relay windings;::of:regenerative-. repeaters f I A9 and i581 associated'rwitheadditive circuit B?- *It .tmay';be .lseeni inlEig. '2 that there :is included in the" circuits to re1ays 53 and '83, armatures'I BQ and IE! to render the relay circuit to regenerative repeaters 53 and 83 inoperative until distributor 2| attains predetermined speed.

As explained above, upon the reception of the start impulse at a regenerative repeater, such as l5, the circuit to the polar relays 53 and 83 is interrupted at the cam controlled contacts at the repeater and remains interrupted until the reception of the stop impulse. Therefore, battery applied over line 5 through contact I53 is effective on the relays 53 and 83 only when the regenerative repeaters have finished repeating the signal impulses and received the stop impulse and, accordingly, there can be no mutilation of the signal combination which would result if the polarity of the relays 53 and 83 were changed during transmission of a code signal combination.

The operation of the transmitting phasing cam 24 and its contacts I53, I54 is as follows: A cam in regenerative repeater I5 moves away from its follower and opens it electrical contact I5I upon receipt of the starting impulse of a permutation code signal, retaining the contact I5I open until receipt of the stop impulse of the code signal. With distributor cams 23 and 24 in the angular positions shown, cam contact I52 is closed connecting conductor I to relay 56 for transmission and contact I 53 is closed to supply negative battery over line 5 to relays 53 and 83, pcsitioning their armatures against their lower contacts and including storage repeater I6 in the transmission circuit. Should a starting impulse begin at this instant at substation II, it would be delayed one half impulse period by'the regenative repeater I5 and the repeated starting impulse would be emitted irom repeater I5 when cam 23 had rotated one half revolution, opened contacts I52 and disconnected conductor I from relay 56; accordingly, the starting impulse must be delayed for a further half impulse period until contacts I52 may be reclosed by the cam 23. Since the starting impulse was received with armatures of relays 53 and 83 against their lower contacts, the storage repeater I6 is included within the transmission circuit. Thus, the starting impulse emitted byrepeater I5 is transmitted into storage repeater I6 instead of into conductor I, and at an instant one half impulse period later it is emitted from storage repeater I6 into conductor I, at which instant the contacts I52 are closed and conductor I is connected to relay 56 for transmission of the impulse into the carrier conductor 51.

A starting impulse initiated at substation II when contacts I52 are open will be delayed for one half signal impulse period in the repeater I5 and therefore, will be emitted from the repeater I5 when the contacts I52 havebeen closed. In such instance, cam 24 will be in a reverse position from that shown in the drawings at the reception of the starting impulse and the reverse polarity of current will be applied to the windings of the polar relays 53 and 83 positioning their armatures against their upper contacts. setting of relays 53 and 83 connects conductor 52 directly to conductor I through the upper contact and armature of relay 53, avoiding storage repeater I6. This condition prevails during the reception of the entire signal combination and, accordingly, a delay of one half unitary signal impulse is introduced into the transmission and the repeater I5 emits the regenerated signal impulses when cam 23 has revolved one half revolution and closed contacts I52, completing the transmission circuit from conductor I to polar relay 56.

This I When both the basic and additive circuits are associated over the synchronous multiplex system above outlined and one circuit is idle, such as basic circuit A, the polarity applied to its associated polar relays, 53 and 83, is reversed at every half revolution of the phasing cam 24 vibrating the relay armatures and connecting the main channel and branch circuitto first one and then the other of the repeaters associated with the particular branch circuit. Upon the receipt of a starting impulse from substation II, the cam controlled contact I5I opens the circuit of the windings of relays 53 and 83 and the condition of the relays as determined then is maintained throughout the transmission of the ensuing code signal. The determined condition of relays 53 and 83 inserts a proper delay in the transmission circuit, synchronizing the transmission from the regenerative repeaters with the operation of distributor cam 23. It is understood that each circuit, basic or additive, is equipped with a delay mechanism such as that already described for conductor I and each operates in preciselythe same manner to maintain proper phase relation between the transmitters and the cam controlled contacts which apportion the line time.

The transmitters in the branch circuits are adjusted to operate at a speed less than the transmission speed of the multiplex. When the branch transmitters are operating at their maximum rate, there will be a gradual shift of phase between the signals generated and the multiplex distributor cams. Accordingly, when multiplex operation has been established and the transmitter in a given branch circuit is operating at its maximum rate, transmission will be through one setting of the regenerative repeaters of that branch for a certain number of complete signal combinations. After the multiplex distributor has crept sufficiently to shift the phase relation of the distributor cams and the signals in that branch circuit, the transmission phasing cam will transfer the branch circuit to the alternate setting of the regenerative repeaters from which transmission will be carried on until the distributor again causes a sufiicient phase shift to return transmission to the first setting of the repeater mechanism. The number of signals transmitted from one setting of the repeaters will depend on the speed differential between the branch transmitter and the multiplex distributor. Ii transmission is from a. keyboard, the rate at which the shift takes place will be quite variable. At the beginning of each signal combination, that branch circuit condition is selected which supplies the best phase relation and this condition is maintained for at least the entire signal combination. When the next signal combination is received, whether immediately or sometime afterwards, that condition of the branch circuit is selected which affords the best phase relation.

To remove the additive circuit from operation and restore the afore-described normal condition, manual key I53 is operated momentarily breaking the holding circuitand de-energizing relays H2 and H3. Relay II 2 releases immediately and at its outer right-hand contacts completes a circuit to supply uninterrupted 1600 cycle current to carrier conductor 51 to operate tuned relay I22 while at its inner right-hand contacts, relay II2 breaks the circuit to slow-tooperate relay I36. By attracting its armature, relay I22 places and holds thearmature of relay I23 against its upper contacts placing a con- -its circuit is now inoperative.

v relay circuits; distributor .At thesame time; relay lfitlinterruptsrtlieciri-i cuitto. slw-to-release relay; I25. 'with erel-ay IAI- tie-energized; the: circuita for relayy G9 is openand-the eXtensioncircui-tfifl, isiacco-rdingly connected: directly to receiver I2 since the; c-irr cults. of the contacts of cam- 33'; are open :at: the armaturesof relay fill andreceiver I46 is-..thereby taken .out-oicircuit, 1

Relay.- I36l then releases-its armature-breake ing. the. circut of relay 58 r causing; it! to; release its. armatures'and de-energ-ize:relay-552.. Relay Slafat its. outer. leit hand .armatureopens:alinezcone ductor 9-, de-energizes relay;- I A-and=extinguishes line. lamp. I 311- to indicate at: substationi' Mia-that At'itssinner, right: hand.contacts relay 55 connects basic-:cirmnt A directly. to extension conductor 3.:re-establishii1g the normal simplex circuit and: disconnectsecon'e duct'or. I. from contacts- I52. Contact. I'I-r is: a m'aKe-b'efore-break. contact, and ccnductor;:;l; is

connected; to extension conductor by; contact ITb'efore beingreleased at the inner..right'L-hand armature. of relay 55.- thus retaining communi-. cation. continuously over. basic circuit A. At its outer ri'g ght.-handv contacts relay. 55;: disconnects additive circuit" B fro-mextension-conductor 3: Relay ii ifdiscoimects atcontacts Itflaandi IB-I the transmitting phasingcam 24 v SIOvv-to-release. relays IIZnand 25 themoperate and-stop motors. 28 .and 38--.- I

The positions. of the armatures=otthe-polar relays at'th'e regenerative repeaters atthetime contacts I68 and H51. arev opened; determine whether. the storage. repeater. it will becluded in thetransmission circuit when.the;sys.- tenr isiagain conditioned for normal operatiom In Fig. 1 storage repeater lfizlS included-.in-the transmission circuit.

To keepcthe. circuit drawingsv clear, there havebeen illustrated at central 'stationlfl'only, one pairof'f branch circuits. A. and B, andiits associated? relay, circuits, distributor. controlled contacts, and transmission phasing, cam for properly" allocating the line. time; of I extension conductor. Cb'etween the branch circuits.- At I8I,,IIl3 and IiiB'therev are "indicated other ex: tension-conductors connected to the carrier con ductorfilandas many such extensionconductors may'bcprovidedas desired;- It is: to..be understood 'thattl lere will be associated .witheach such extension conductor a. pair. of branchv circuits;

a transmission phasing cam ineX-actly-r' the. same manner as described in detail .for extensioncon! ductor' C." In'operation each eXtensionconductor of the system'will modulate an alternating current oia distinctive frequency in aimanner well known'in' carrier systems.

At central station 353' there areshownialtuned relay 9'6, actuated by signals receivediov er car.- rier-conductor lEi', afpclarrelay 93; distributor controlled-contacts rep-resented at. M; .and relay circuits and repeaters indicated'at 95 tOmaSSO'r ciatesubstations" 98" and I 1 QB" with tunedrelay 90.- At- H32 and Ifi l are representediadditional extension conductors at central station 3Ill-with which" similar" means. is provided. to. complete communication thereover inamannerrcontemplatedby thisinvention. Although a carrier system hasbeendisclosed, the invention is by nomeansslimited thereto and. the extension conductors-sot central: offices 20; and: air ma be. directly; connectedi affording controlled contacts; and

provide aisynchronizingzctx'anneh With snch a circuimaarrran-gement; depressing: lkem II I- would-:starirmotordfi 'atiicentralgofficeifl andimoe tor: 38 :at. centra'hofirce: sfizrinisynchronismrand 1 phase: to; simultaneously} iestablish multiplex. oration oversea plurality: ofi distinct-a circuitssand the; synchromzingschannel-r would. assure: the groperrphasingrofi thessubstation: apparatus: and thadistriliuton the: same: manner asrsthat described for thesystemrdisc'losed iniEigszalz and 22.; Direct. current; signals then, oi-v course; be: usech implace: of a: modulated carrier current:

I Ifrcliuidimig'chumzel. orientation. e Eachifollower for cam 3sciseshowninpFia z as mounted ononegarm:ofitarbellzcranke. AdLca/m followers: in the: receiving; distributor; are :thus mounted. Theedetailseare' shown 1in-1Eig. 5;.

If: desired,- asingle means .rmaycrbe: provided) to adjust both camilfollcwers sirnultanecusly Such an". arrangement-w is aillustra-tedzin-fig 6:; wherein the adjusting means is-illustrated: inw connection with armultirlobe cam whosez utili-ty isto lbenointe edmutv subsequentlyz. 0icourse, thinadjusting device; readily; be. employed with: the: cam demonstrated in' Fig; 5

In Fig. .firoc-ke-r memberyl"! i is niyotedntotthe frameeatt. I='I 2'- and; carries; c-ainjfollower:113v as well lasacam i followeri I 644;, Both 10am followers; ISA-1* and; I13; pertain ato..;tl'ret sane-e \entensionscons ductorand are thus adjustable by! oner rocker member. andthumb screw. ThGF'mBmDI-MSe in- Eig. 6 vvhichare similar: to-memberseinl igc 5 bear similar-numeralsprimed-i. v

*M'lbliiiiZ-Zblkd" came The distributors. shown in Rig. 2: illustrated with cams of..a .single.-lobe; and shaftsufia andcez are presumedvto'rotateat aspeed ofloneirevolur tionl per signal; impulsexlinestimer perioolz', Itl'lS' pcssible to increase thei numberrof .lbbSfzOUIT-Bflfih cam and proportionately; decreases-thee.rotational speed. of the 51272211135222? and;- 32 i In: Eigz. 6:; seven lobes: IJ4- v aresshowni on cam: 331i" corresponding: to canrr. 33.; and .shafti fii; corresponding to shai-t 32, isipresumed to rotate at a'-- speedof fone re'v o-lution per -jiunit codesignal tiine period? rtrst mowi eauony v, Ei'gs: LZiandzSswhem combined ipresenttcompletecircuttsiil'lustrating 'ai'zmodificatiorit of the==system transmission line. In the mechanical relay 32I,

a motor driven shaft 323 acts through friction disc 324 of a friction clutch not otherwise shown to drive two integrallyunited wheels, namely,

ratchet wheel 325 andcam wheel 326, which are restrained either by armature 321 or alternatively by armature 328. A cam follower 33I rests on a lobe of cam 326 and holds contacts 332 and 333 in operated condition '(as shown in relay 32I) when ratchet 325 is restrained by ar-' mature 321, or permits the contacts 332-to assume unoperated contactual relations with respect to contacts 333 when ratchet 325 is restrained alternatively by armature 328 and cam follower 33I rests in a depression of cam 326 (as shown in relay 322) A Magnets 335 and 336 control armatures 32'! and 328, respectively, and are energized alternatively by current over conductors 329-429,

right-hand winding of relay 55, contact I60 to contacts I53, or conductors 330I 30, center winding of relay 55, contact I 6| to contacts I53 of cam 24, and conductor -305 through cam controlled contacts 3I9 and 35I to ground.

With the circuits of Fig. 3 coupled to those of Fig. 2 there is illustrated a communication system having both a normal and alternate condition identical to that of the system disclosed in Figs. 1 and 2. Accordingly, the description of Fig. 3 will be limitedto the operation of the mechanical relays and it will be assumed that the alternate condition of the system has been established connecting substation 3I I over conductor I of the basic circuit and substation 348 over conductor 302 of the additive circuit to 8X- tension conductor 3 because, until that condition i established, the mechanical relays are held in one position since the circuits to magnets 335 and 336 are open at contacts I60 and I6I.

When shaft 22, Fig. 2, is operating at synchronous speed and neither regenerative repeater 3I5 nor 3I6 is repeating a signal combination, contacts I53 of cam 24, will supply current from negative battery, Fig. 3, alternately through magnets 335 and 336. The circuits are: ground, cam contacts I and 3I9, line 305-5, contacts I53 at cam 24 then to either line I29, contacts I60, right-hand winding of relay 55 to line 329, magnet 335 and battery or to line I30, contacts I6I, center Winding of relay 55, line 330, magnet 336 and battery. When cam 24 is in the angular position illustrated in Fig. 2, magnet 336 is energized, ratchet 325 is restrained by armature 321, follower 33I is resting on a lobe of cam 326, contacts 332 and 333 are closed, and the magnet of storage repeater 3I6 is energized by current flowing from positive battery, through magnet of storage repeater 3I6, operated contacts 333 and 332, conductor 352, contacts of regenerative repeater 3I5, and'battery. If the start impulse of a signal combination were received by regenerative repeater 3I5 at such an instant, the repeater would start and would open the cam controlled contacts 35I, breaking the circuits to-both magnets 335 and 336, thus retaining the cam 326, follower MI and contacts 332-333 in the condition illustrated, and resulting in the operation of storage repeater 3I6 in response to the operation of regenerative repeater '3I5. The contacts of storage repeater 3I6 then would operate to transmit signals over conductor 30I--I to relay 56 and to the carrier conductor 51. In this condition with repeaters 3I5 and 3I6 in the transmission circuit, a delay of a full signal impulse period is introduced'in thetransmission, as was true of the corresponding condition of the apparatus of Fig. 1. Because of the cam controlled contacts at each regenerative repeater, this condition prevails until the transmission of an integral number of complete signal combinations.

When cam 24 is in its alternative angular position, with its controlled contacts I53 in reversed contactual relations, magnet 335 is in energized condition, ratchet 325 is restrained by armature 328, follower 33I is in its lowered position, contacts 332333 are open, and the magnet of storage repeater 3I6 is energized by current fiowing from positive battery, through the magnet of storage repeater 3I6 and unoperated Since those contacts are not closed until the reception of the stop impulse,

mutilation of the'signal comder the control of the cam contacts of repeaters conductor 306 6, contacts I54 of cam 24 and return conductors I55 355,

storage repeater into and out of the translnlSSlOIl path from substation 348 to conductor 302-4 and to relay 56. At 345 is the line relay operative to illuminate lamp 1. In atelegraph system, a main channel, a branch c1rcu1t, means to establish start-stop simplex operation over said main'channel and branch circuit, means to establish synchronous multiplex operation over said main channel, and means to maintain said simplex operation until said synchronous multiplex operation is completely established.

2. In a telegraph system, a synchronous multiplex channel, a start-stop circuit extending from said synchronous multiplex channel, synchronous telegraphic apparatus at each terminal of said multiplex channel and operable over said synchronous channel, start-stop apparatus operable over said start-stop circuit, means to condition said main channel and said start-stop circuit for simplex operation, means at one end of said synchronous channel to start into operation and to properly phase the apparatus at each terminal of said synchronous channel, and means to change the operation of said synchronous channel to synchronous multiplex operation when said synchronous apparatus attains proper speed.

3. In a telegraph system, a main channel, a branch circuit extending from said main channel, synchronous telegraphic apparatus operable over said main channel, start-stop telegraphic apparatus operable over said branch circuit, means to operate said main channel as a synchronous multiplex channel and said branch circuit as a start-stop simplex extension channel,

means to establish start-stop simplex operation over said main channel and said branch circuit, and means to disable said synchronous operation over said main channel and establish said start-stop operation.

4. In a telegraph system, a synchronous multiplex channel, a plurality of start-stop simplex circuits, one of said simplex circuits being normally connected with said multiplex channel for start-stop operation, means to establish synchronous multiplex operation of said plurality of start-stop circuits over said multiplex channel, and means to maintain said normal start-stop operation over said one of said simplex circuits and said multiplex channel while changing said multiplex channel to synchronous multiplex operation.

5. In a telegraph system, two stations, a plurality of channels connecting said stations, telegraph apparatus at both of said stations, means controlled over one channel to synchronize said apparatus, means included in said synchronous apparatus to control signaling over the remaining channels, and means controlled over said synchronizing channel to alter the number of available signaling channels.

6. In a multiplex telegraph system, a synchronous multiplex channel, a basic circuit and an additive circuit, a relay having a plurality of sets of contacts, said basic circuit being normally connected to said multiplex channel through one set of said contacts establishing a simplex-telegraph circuit over said basic circuit and said multiplex channel, synchronous telegraphic apparatus operable over said multiplex channel, means to start said synchronous apparatus, and means to energize said relay and connect said basic circuit and said additive circuit to said multiplex channel through the remaining sets of contacts of said relay for establishing a multiplex system, said last named means being operated when said synchronous apparatus is operating.

7. In a telegraph system, a synchronous multiplex channel, a pair of start-stop circuits each including a transmitter, a mechanical distributor, means to operate said distributor, said distributor having two pairs of distributing contacts, each pair of which is connected between said multiplex channel and one start-stop circuit, said pairs of contacts being operated to connect said transmitters in alternation over said start-stop circuits to said multiplex channel, means for stopping said distributor, and means for disconnecting both of said start-stop circuits from said pairs of contacts and for connecting one of said start-stop circuits permanently to said multiplex channel for simplex operation thereover. I

8. In a communication system, a multiplex channel, a pair of start-stop circuits, a mechanical distributor comprising two pairs of contacts, each contact pair being connected between said multiplex channel and one of said start-stop circuits, means to operate said distributor and establish synchronous multiplex operation over said multiplex channel and said pair of startstop circuits, and automatic switching means operable to disable said multiplex operation and to connect one of said start-stop circuits with said multiplex channel for simplex operation thereover.

LOUIS M. POTTS. 

